EXTERNAL RELEASING SPEAR Russian patent published in 2003 - IPC

FIELD: fishing tools, particularly, external releasing spears of collet type for withdrawal of failed pipes from wells. SUBSTANCE: external releasing spear has body consisting of upper and lower parts. Body lower part accommodates changeable funnel in form of wing with long and short parts. Long part has pointed end from inner part. Short part is made with cone secured to catching member. Installed in lower part are catcher, spring-loaded rod rigidly connected with hollow cylindrical rod, branch pipe in lower part of rod under spring. Catcher is made in form of hollow cylinder with widened part in end and cut-off side and internal surfaces. Rigidly secured between body upper and lower parts is locking member in form of guide hollow cylindrical bushing of variable cross-section. Catching member is made in form of changeable collet fastened between body lower part and catcher. Shaped bushing is installed as retainer of motion between body upper part and hollow rod with bearing bead. Shaped bushing includes two rows of wedges with guide and deflecting surfaces. Vertexes of wedges are directed opposite to each other with gap exceeding pin diameter by 1-2 mm, guide surface of wedge is formed by straight line, and deflecting surface is inclined in upper row, and inclined and straight lines in lower row. Vertexes of wedges between guide and deflecting parts are made with chamfered sections in upper row and doubly chamfered sections in lower row. Upper row of wedges is made in form of fork-shaped members with two wedges in end and rounded recess between them. Fork-shaped members have longitudinal recess between them. Wedge lower row has longitudinal recesses located between wedges. Sub is located at end between body and spring- loaded hollow rod and rigidly secured to them. Pin is rigidly connected with body internal surface at level of wedge upper row and located in rounded recess. EFFECT: higher operate reliability of component members and design as a whole, extended field of application. 5 dwg